The use of agricultural chemicals often results in water pollution. This research, comprising three parts, was designed to investigate the role of soil and grass strips and water table management in reducing pesticide and nitrate residues in drainage waters. / The first part of the research was made on lysimeters to investigate the effects of soil and grass cover under two water table management regimes. Four treatments were involved: subsurface drainage, controlled drainage, grass cover, and bare soil. Each treatment consisted of three replicates. Contaminated water containing atrazine, metolachlor, and metribuzin residues was applied to the lysimeters and samples of drain effluent were collected. Significant reductions in pesticide concentrations were found in all treatments. / In the first year (1993), herbicide levels were reduced significantly, from an average of 250 mug/L to less than 10 mug/L. In the second year (1995), water polluted at a concentration of 50 mug/L, was applied to the lysimeters, and herbicide residues were reduced significantly to less than 1 mug/L. Subsurface drainage and grass cover lysimeters (SDG treatment) reduced herbicide concentration levels to a greater extent than the other treatments and the controlled drainage lysimeters reduced nitrate concentration levels to a greater extent than the free drainage lysimeters. / The second part of the research was a field study that reports the development and testing of an on-farm pollution control system using soil as a biological filter for trapping herbicide residues. A field site with four shallow surface ditches, underlain with four perforated drain pipes, was used to carry-out field measurements. Polluted water with concentration levels of 30 mg/L of nitrate and 100 mug/L of three commonly-used herbicides was applied to the ditches for 10 days continuously; and no water was applied for the following ten days. This cycle was repeated three times. Water samples were collected both before application and after the water came out of the drains. Herbicide levels were reduced significantly in drainage waters. The average concentration level of nitrate in drainage water was found to be 17 mg/L in comparison to 30 mg/L in applied water. Also, the bio-degradation of herbicide residues in the soil was found to occur between water applications. Thus, it appears that the system would be self-sustainable in the long term. / The third part of the research utilizes a water table model, DRAINMOD, for simulating drainage waters from agricultural land and a solute transport model, PRZM2, for simulating pesticide concentrations in the drain effluent coming out of the grass filter area. DRAINMOD was used to estimate the daily drain outflows that would occur in a 100 ha subsurface drained field in the for a 1-in-20 year annual rainfall period. It was found that 6% of the farm area could be used to bring down the concentrations in drainage water from 50 mug/L to less than 1 mug/L for the three herbicides. (Abstract shortened by UMI.)

No description available.

This study determines the effects of variations in suspended biomass, organic carbon, and pH on the time course of 2,2$ sp prime$,4,4$ sp prime$,5,5$ sp prime$-hexachlorobiphenyl uptake by laboratory cultures of Selenastrum capricornutum. Variations in pH had no effect, but uptake was enhanced by higher levels of biomass and depressed by higher levels of organic carbon. The coefficients for these measured effects on hexachlorobiphenyl were combined with existing relations based on molecular connectivity (X) or capacity ratio (K$ sp prime$) to yield semi-empirical equations to predict the instantaneous rate of uptake and bioconcentration factor (BCF) of organic contaminants as: eqalign{& rm Log rate = {-}3.30 + 0.32 X + 1.1 Log biomass {-}0.42 Log Abs cr& rm Log BCF = 4.11 + 0.86 Log K sp prime {-}0.87 Log biomass {-}0.22 Log Abs cr} / The utility of these equations was assessed by comparing time courses of hexachlorobiphenyl uptake predicted from them with time courses observed in water from eleven Quebec lakes.

Despite the pollution control provisions provided in national and local legislation that explicitly or implicitly give effect to the polluter pays principle (PPP), certain rivers continue to suffer from persistent industrial pollution. This research focuses on one such river, the Bayne's Spruit, as a case study. The Bayne's Spruit is a small river that is located within an urban catchment, and which has been subjected to wet industrial pollution for over a decade. Much of this pollution is associated with the Pietermaritzburg edible oil industry. This pollution impacts negatively on a downstream community that uses the river for irrigation of subsistence crops, for recreation and for subsistence fish harvesting. The pollution has also severely degraded the riverine ecosystem. This research commenced with a literature review of the PPP in its international, national and local context. It was noted that the current legislative framework for implementation of the PPP with regard to pollution of rivers in South Africa comprises primarily of the National Water Act 36 of 1998 (NWA), the National Environmental Management Act 107 of 1998, and the Pietermaritzburg-Msunduzi industrial effluent bylaws of November 1998. The case study was approached using a largely qualitative methodology, although quantitative data was also relied upon where feasible. The historical context of the case study was provided by conducting a review of newspaper reports, a review of. government inspection records, and a review of water quality data (including biomonitoring and chemical data). The current status of the Bayne's Spruit was then explored by conducting in-depth historical interviews with community members, and by conducting direct observation of the environmental status of the Bayne's Spruit. This data was supplemented by an analysis of the test results of sampled industrial effluent, and by information obtained from representatives of two edible oil companies. In-depth, purposively selected interviews were conducted with various role players. (local government, regional government and industry) to identify what factors are preventing the successful implementation of the PPP in the case study area. Factors identified include a lack of environmental ethic within the edible oil industry, with some of these companies free riding on the Bayne's Spruit to maximize their profits. At a local level, factors preventing implementation of the PPP include deficiencies in the local industrial effluent bylaws, failures to administer and implement provisions contained in the bylaws, capacity restrictions and institutional paralysis. National legislation is not being successfully implemented because the government agency empowered under the NWA is deferring primary responsibility for dealing with pollution to the local authority. Factors also include difficulties associated with monitoring of rivers, including lack of capacity to engage in monitoring, and confusion over the functions of the various spheres of government. Finally, enforcement complexities are a major factor preventing successful implementation of the PPP. These problems relate to inadequate penalties, enforcement arrangements, capacity problems, separation of authority to operate the municipal sewer works and to enforce the industrial effluent bylaws, difficulties in identifying the offending polluter (causation), problems with access to company premises, the open access character of the storm water drainage system, previous failed prosecutions and reliance on the criminal justice system. / Thesis (M.Sc.)-University of Natal, 2002.

No description available.

No description available.

The present project aimed at measuring plant heavy metal uptake as a function of transpiration rates and dissolved heavy metal level in the soil solution. Two experiment was conducted separately in two season (Spring and Fall 2000). In these two experiments, young wheat plants ( Triticum aestivum) were irrigated with nine different solutions containing Cd and Zn. The study was conducted in two chambers where relative humidity was controlled to obtain two different levels of transpiration rates. Each control chambers contained 27 pots filled with sand and seeded with wheat plants, each nine triplicated pots receiving a different treatment: three Cd treatments with levels of 0.01, 0.10, and 0.50 mg/L; one Zn treatment with level of 25mg/L and four treatment combinations of Cd/Zn with levels of 0.01 Cd/25Zn, 0.10Cd/25ZN, 0.50Cd/25Zn and 0.50Cd/50Zn mg/L. The transpiration rate of the plants was monitored over a period of 30 days, measured from the emergence of the plants by weighing the pots daily. On day 15 and 30, three plants were removed from each pot, to weigh their dry matter production and to analyze their heavy metal uptake. (Abstract shortened by UMI.)

Nitrate discharges from diffuse agricultural sources have long term effects on groundwater and surface water quality. Market-based instruments have been proposed as a means of balancing the demand for nitrate intensive farming and the capacity of the natural water bodies to dilute nitrates. Trading is complicated by the dispersed, delayed, and protracted effects of diffuse sources. Market mechanisms proposed to date have failed to incorporate these physical characteristics of nitrate pollution correctly. We propose a new market mechanism for allocating and pricing nitrate discharge permits, based on the design of modern electricity markets which use LP models to find optimal prices and dispatch schedules. The system operates as a centralized auction. The sources submit bids to the auction indicating the benefits gained from each unit of nitrate discharge. The auction operator runs an LP which maximises the benefits from trade, subject to a set of environmental and operational constraints. The LP solution produces the optimal prices and allocations relative to the economic values indicated in the bids. Our contributions include alternative LP models to suit different hydro-geological and socio-economic conditions. We present a generalized LP model which can include constraints that describe nitrate residence and transport in groundwater and surface water, the ability of water bodies to accept nitrates, and the operational limitations of the commercial sources. We show how to adapt available methods to incorporate the complex physical systems into an optimisation model. We present a double-sided market model which allows the polluters to buy permits, and environmental agents to lease out the ability of the natural water resources to accept nitrates. The model allows the providers of environmental services to participate in the market as sellers. We build up and prove the concepts by explaining the prices and allocations produced by the LP models. Based on the theory of nodal pricing applied in electricity markets, we discuss the price structures and relationships and show how the prices would reflect the spatial and temporal effects of diffuse nitrate discharges. We interpret the information generated from the outcomes of trading and discuss how the available tools and information can be used by the market participants to optimize their bids. We expand the proposed market model to include point sources, and identify the factors that determine the extent to which the point and nonpoint sources can trade with each other. In addition, we develop measures of the extent to which the diffuse sources themselves can trade with each other. We demonstrate the models and the resulting prices and allocations, using a catchment nitrate transport model.

Orthophosphate removal from wastewater in a subsurface-flow constructed wetland (SFCW) was studied during the fall of 1995. The SFCW consisted of a cell with an impervious liner, filled with 1.27 to 3.81 cm river rock and planted with common reeds (Phragmites australis) and soft-stem bulrushes (Scirpus validus). Municipal wastewater was pumped through the wetland and comparisons were made between inlet and outlet orthophosphate concentrations. Comparisons were also made at locations within the cell. A mean orthophosphate reduction of 62% with a range of 91% to 32% was observed for the duration of the study. An ANOVA test showed a significant reduction of orthophosphate in the wetland cell during the study. A regression analysis indicated that inlet wastewater temperatures played a significant role in orthophosphate removal, while outlet wastewater and ambient air temperature were not a significant factor.Keywords: Subsurface-Flow Constructed Wetlands, Orthophosphate, Municipal Wastewater, Water Chemistry, Nutrients. / Department of Natural Resources and Environmental Management

The thesis explored the effect of government regulation on the cost of developing Facility Plans for pollution abatement facilities in Indiana. The study used cost data from nearly 300 sewage works projects across Indiana from 1968 to 1976. The cost of professional services for these projects was computed on a per capita basis for each fiscal year and fluctuations in cost were analyzed in light of regulatory changes.It was found that the effect of these regulatory changes was to escalate costs, especially in fees for projects in municipalities with less than 2,000 population. / Department of Urban Planning